Currently available white noise machines can be categorized into one of two categories: digital or acoustic. Digital white noise machines typically employ an audio speaker system to produce sound. On the other hand, acoustic white noise machines typically produce sound by using a fan blade system to generate noise.
The design of currently available acoustic white noise machines has not changed substantially for over fifty years and suffers from a variety of drawbacks. First, due to its reliance on moving sound porting closer and further away from a sheared airflow edge, the established design is limited to only controlling the volume exuded from the device without enabling the user to control the actual broadband turbulent noise created. This is because the current design does not provide for controlling the amount of air flow sheared which remains constant. Consequently this drawback significantly limits the variability in sound that can be produced by the device.
Further, the existing design depends on increasing airflow speed to increase volume. However, increased airflow speed also necessarily entails the increase of blade passing frequency and other undesirable phenomena which detrimentally impact sound quality. Therefore, this shortcoming also limits the potential volume range of the device. Added to the limited volume range are the ineffective overlapping methods of controlling the levels of the noise volume produced by the device. The prevailing design employs a combination of adjustable top vent holes and an outer rotating disk each operating independently to adjust the tone generated by the device. This arrangement results in a number of overlapping settings that are unnecessarily complicated and ineffective for accurately obtaining the desired tone.
Another drawback of the design on the market today is the significant air outflow produced by the device. Considering that the purpose and operating principle of the system is converting the kinetic energy of the air being driven by the fan into sound energy, having excess air outflow is indicative of wasted energy. However, the substantial cold air outflow is not simply a latent inefficiency of the design but is also a highly undesirable feature. This flaw may be especially detrimental if the device is used near cribs, which incidentally also highlights another widely noted drawback. In particular, as one of the most frequent uses of white noise machines is soothing infants to sleep, aside from cold air, safe volume limits also become an oft-cited and significant concern. As these units often remain on up to 8-12 hours per night, safe volume limits should be based on the prolonged continuous duration of device operation. The white noise machines currently available to consumers do not provide users with the means of ensuring safe operating volume during usage.
Finally, there is also a lack of any white noise machines configured to be controlled remotely without necessitating physical interaction with the device, as well as a lack of such machines which provide dim illumination to serve as night-lights during night time operation. For the foregoing reasons, there is a need for an acoustic white noise machine which is efficient and safe to use in a variety of settings and whose volume and tone can be accurately controlled. These and other features and advantages of the present invention will be explained and will become obvious to one skilled in the art through the summary of the invention that follows.